Obstruction horseshoe kidney

Risk factors are male gender, smoking, coffee drinking, anatomic abnormalities like obstructions or horseshoe kidney, and exposition to chemical carcinogens like aniline, aromatic amine, and benzidine, as the metabolites of these substances are excreted into the urinary tract. 

Ureteropelvic junction obstruction by a high ureteral insertion or an anomalous renal vessel is the most common cause of hydronephrosis, which occurs in 30% of patients diagnosed during life. Urolithiasis develops in 20% of patients with a horseshoe kidney. Stasis secondary to hydronephrosis, but with metabolic factors are also the reasons (Evans and Resnick 1981). 

Horseshoe kidney may present UPJ obstruction due to the crossing between the vessels and the ureters. This usually involves one of the collecting systems (Fig. 5.19). 

Fig. 5.19. UPJ obstruction and horseshoe kidney. Left side UPJ obstruction on the IVU...

Contralateral VUR may be present in about 10%-20% of patients with multicystic dysplastic kidney (Fig. 11.29). VUR is also present in a significant number of other uropathies, i.e., horseshoe kidney, crossed fused kidney, UPJ, and UVJ obstruction. Therefore, in any anomaly of this type, a VCU should be advised for a complete workup (Atiyeh et al. 1992 Ring et al. 1993 Song et al. 1995 Avni et al. 1997 Cascio et al. 1999). 

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